“The fastest known enzyme is catalase. Found in the liver where it speeds up the decomposition of hydrogen peroxide into water and oxygen, catalase has a turnover number [the number of substrate molecules which one molecule of enzyme turns into products per minute] of 6 million. Its action can be demonstrated by dropping a small piece of liver into…hydrogen peroxide: the fizzing that ensues as oxygen is given off is a dramatic demonstration of an enzyme in action.”
M.B.V. Roberts, from "Biology A Functional Approach"1986
Method:
The equipment used will be: 3 test tubes, a test tube rack, 3 stop watches, protease solution, in this experiment it is Trypsin, (3 kinds of enzyme concentration: 0.5, 1 and 2) and a milk powder solution (the protein solution). 5cm Pipettes to put the substances into the test tubes.
For safety goggles should be worn as chemicals are being used. Also minor fumes may be given off, so be careful not to breathe them in. Avoid spillages onto bare skin as it may be harmful, rinse under cold tap if this is the case, especially in the result of any solution going into a person’s eye. Do the experiment at a good pace as not to spill or knock over any fluids or equipment. These safety measures are in place to avoid any harm to people involved in the experiment and to avoid any accidents.
- Prepare a work space, and then collect the equipment. When collecting the substances be careful as to not let any make contact with the skin, it isn’t dangerous but it’s advised to be cautious. Also try not to inhale any of the fumes possibly given off during the experiment.
- Clean the test tubes to make it valid test and take out the variable of any other substance in the test tube. Clean the test tubes by rinsing them out with distilled water; this will remove any unwanted substance.
- Start to set experiment up, place the test tubes into a test tube rack, and then put the 3 different concentrations of protease solution into the 3 separate test tubes. 5cm should be put into the test tubes to once again make it a valid test, measure it by using a pipette to gather the solution.
- Add 5cm of milk powder equally to all of the test tubes which are filled with the protease solution and as soon as the substances are combined, stir and gently shake the solution to mix it up more.
- Start the stopwatch as soon as the solutions are starting to be mixed, do this for the other 2 test tubes as well but 1 after another.
- Keep a close eye on the solution during the experiment as not to miss the change in clarity.
- Only stop the time once the solution has gone translucent or so you can see through it onto the desk you are working on.
- Make a results table up and record your results in minutes.
- Repeat the experiment 3 times to get a range of results.
Results:
Discussion:
Test stick to compare translucency: This should be used as to avoid any confusion to what the correct result of the experiment should be.
Enzyme concentration increases the rate of reaction-higher concentration quicker time to react: This was expected to happen because an enzyme is a biological catalyst and so this speeds up the reaction. Raising the concentration would therefore decrease the time taken for the 2 solutions to mix.
Person timekeeping starting at different set off points and stopping at different ending points: This could make the results invalid if a different person was watching and timekeeping during the experiment as peoples reaction times differ.
Summary:
In this experiment I investigated how enzyme concentration can affect the rate of a reaction. I found out that the higher the enzyme concentration, in this case Trypsin being the enzyme, the quicker the rate of reaction on an average scale. I also found out that the Trypsin turned the Milk powder substance translucent when it mixed in with it. This tells me my Null Hypothesis was wrong and that enzyme concentration does alter the speed of a reaction and that the enzyme used Trypsin was a catalyst in the experiment.
